Multioffice telephone system



June 16, 1925.

B. D. WILLIS MULTI OFFICE TELEPHONE SYSTEM 4 Sh eets-Sheet 1 FiledMay a; 1921 4 Sheets-Sheet 2 JILL/En Ur Barnard D, M11115 Filed May 3 1921 B D WILLIS MULTIOF'FICE TELEPHONE SYSTEM June 16, I925. 1,542,649

B. D. WILLIS MULTIOFFI CE TELEPHONE SYSTEM Filed May 5, 1921 4 Sheets-Sheet 5 --Inu5n [Ir- Bernard Dlnfflhs June 16, 1925. 1,542,649

B. D. WILLIS MULTIOFFI CE TELEPHONE SYSTEM Filed May 1921 4 Sheets-Sheet 4 I1'LUE1'L nr- Barnard Dlnfllhs 777 5m Patented June 16, 192 5.

UNITED STATES PATENTVOFFICEJ.

BERNARD D. WILLIS, 01!. OAK PARK, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRIC COMIANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

- cuit arrangements Application filed May 3,

network offices or exchanges of two dif-' ferent kinds, the oflices of one kind being manual ofiices wherein connections arecom" pleted by operators, while the other kind of offices are automatic offices in which connectionsare completed by means of automatic switches, and the object of the invention is to provide new and lmPI'OVedIIHP:

cuit arrangements for handling 'inter oftice calls between the automatic and manual ex- Systems having both kindsof exchanges as above pointed 'out are becoming quite common and may arise either by consolidation .of existing manual and automatic sys temstserving the same territory, or by the process of changing over a manual system to an automatic system. Usually in the latter case only one office at a time is converted from manual to automatic and it follows that during the period of transition there will necessarily be both kinds of offices in operation. However this situation may arise, it is necessary to provide suitable cirfor handling calls from the manual offices to the automatic oflices, and from the automatic offices to the manual offices. The present invention is concerned only with the latter class of calls, and provides certain improvements in a system comprising automatic to manual trunks which are accessible to selector switches in the automatic ofiices and terminate in plugs in front of B operator at the manual oflice, together with call registers for registering the digits in telephone numbers called by automatic subscribers when the trunks are taken for use, and an indicating device upon which such numbers are shown to the operator one after the other as fast as .she can complete the desired connections.

The present invention may be considered o be an improvement on thesystem dis- MuL'rIorFIon TELEJPHONE SYSTEM.

1921; Serial No. 466,446.

closed in my prior application, Serial No.1

calls to .the operator in order to prevent unnecessary tylng up of equipment and delay on the part of calling subscribers; in the provision of speclal call and supervisory lamp circuits whereby the supervisory lamp 1s lighted in place of the call lamp in case thelatter should be burnt out; in the provision of improved call register circuits which renderthis part of the system better adapted for practical use; and-in the provision of various other detailed improvements, all of which will be pointed out and described fully in the detailed specification which follows:

In the drawings, comprising Figs. 1, 2, 3, and 4, there is shown by means of the usual circuit diagrams the apparatus and circuit connections thereof which is involved in apomplete connection extending from the automatic substation A Fig. 1, to a manual substation A, Fig. 2. i The apparatus indicated in-Fig. 1 is located in an automatic exchange, while the apparatus indicated in Figs..2, 3, and 4 is located in a manual e'xchange. Inasmuch as the automatic switch-' mg equipment itself and the manual equipment are both well known and of the usual type, no detailed description of the mechanical features of this apparatus will be given except in'so far as it is found convenient or necessary to do so in theexplanation of the operation of the circuits.

Referring to Fig. 1, the substation A is one of a plurality of ordinary automatic substations terminating in the automatic eX- selector of the well-known Strowger type.-

In a multi-oflice system of the kind. herein contemplated the first selector switches are usually known as office selectors and the selector Dv in common with a .plurality of similar selectors has access to a plurality of groups of trunk lines, each of which groups may extend to adifferent oflice or exchange in the system. Some of these groups of trunk lines may extend to automatic exchanges, while other groups may extend to manual exchanges. A trunk line in one of thelatter groups is shown inthe drawing,

and comprises conductors 76, 77, and 78,

which extend to the manual exchange in question and there terminate in the plug ending cord circuit 0, Fig. 2. The cord circuit -0 is one of a plurality of similar cord circuits at a B operators position. in the manual exchange and constitutes the means whereby the trunk line shown may be connected by the operator with any one of the manual lines terminating in the manual exchange. One of these lines is the line of substation A, which with its associated line equipment isshown at the right of Fig. 2.

From the foregoing it will be understood that the operation of an oflice selector, such as the selector D, in response to the calling of the first digit in the telephone number of a line in the manual exchange, will result in extending the connection from the line of the calling automatic subscriber to an' idle plug ending cord circuit in the manual exchange. In order to take care of the remaining digits in the numbers there is provided for each B operatorsposition a plurality of register sets as hereinbefore stated, each set being capable of registering all the digits in a telephone number, with the exception, ofgcourse, of the first digit which controls the ofiice selector in the auto-. matic exchange. In Figs. 3 and 41 have shown one of these register sets complete. It comprises master control switch MS, Fig. 3, and register switches R R R and R Fig. 4-. The. master control switch MS, which may be described briefly, consists essentially of two wipers 255 and 256 and their associated sets of bank contacts, to gether with a stepping magnet 259 for advancing the switch'wipers, and a release magnet 258 for restoring them to normal.

A set of rotary oif normal springs 257 are included in the circuit of the latter magnet and are'closed on the first movement of the switch. .Since' the switches are all alike mechanically it will be unnecessary to de-- scribe the others.

The indicating device by means of which called telephone numbers are shown to the operator is shown in -Fig..4-where it is in dicated 'by reference character V. It com-' prises, essentially, a plurality of banks of 5 switchboard lamps, there being one bank of lamps for each register switch in a register" set. It will be understood that the lamps have the function of illuminating the digits of the called numbers and causing them to stand out so as to be readily distinguished. The digits are' preferably marked in black on the reverse side of a white semi-transparent surface and ordinarily are not very conspicuous. But when the switchboard lamp immediately behind any character or figure is lighted such character or figure will stand out very clearly and is read with great facility. There are two of these indicating devices, one of which is held in 90 reserve for emergencies while the other is being used. The lamps in one of the indicating devices are wired to the bank contacts which are associated with wipers 304, 324, 344, and 364, of the several registerswitches of the register set shown, and are also wired to similar contacts in the banks of the register switches of the other register sets at the position. The lamps of the emergency indicating device are similarly wired to the bank contacts associated with wipers 305, 325, 345, and 365, of the register switches in the register setshown, and of course are also multipled to the corresponding bank contacts in the register switches ofthe other register sets.

In case the indicating device in use should get out of order, as for example, if some of the lamps should have to be replaced, the emergency. indicating device can be connected in by actuating the key K at the operators position, which transfers the switching through ground from the upper banks to. the lower banks. As stated hereinbefore, there is a plurality of register sets providing forthe registration of a plurality of calls simultaneously or close together. These registered calls are displayed on the indicating device one after the other as fast as the operator can complete the Connections by plugging into the'multiple jackswhich correspond to the numbers displayed. In order to switch the calls over onto the .indicating device in succession a so-called consecution control switch is provided. This switch is shown in Fig. 2 where it is indicated by reference character COS, and comprises a single wiper and bank of contacts as shown in the drawing. The switch COS is mechanically the same in construction as -wiper has no normal position and moves in a forward direction only. The circuits, however, have been changed and will be described hereinafter i a Each register set is provided with a time controlledswitch which .in the case of the register set shown'in Figs. 3 and 4 is indicated by the reference character P, Fig. 3. The switch .P is similar in construction to the register switches but is operated by a timing mechanism instead of by means of impulses corresponding to digits in the called telephone numbers.

The timing mechanism, which may be common to the exchange, is indicated by the reference character T, and may consist of any suitablekind of clockwork controlled mechanism which is adapted to produce impulses at the rate of one per second.

In order to properly extend calls which are received at the manual exchange to'the register sets each cord circuit is provided with an individual rotary line switch as hereinbefore explained, and thesev line switches havecommon access to all the register sets. The reference character C, Fig. 3, indicates a rotary line switch which 1s individual to the cord circuit 0, Fig. 2, and which has access to the register set shown in the drawings, assumed to be the first, and also to the other register sets which are provided at the B operators position in which the cord circuit O'term'inates. Line switch C is of the sameconstruction as the line switch C, Fig. 1, although the circuits are modified somewhat in order to take care of the somewhat different requirements.

Having described in a general way the layout of the system herein disclosed, the

operation of the circuits will now be de-- scribed more in detail, it being assumed for this purpose that the subscriber at. -substation A, Fig. 1, desires to obtain a connection' with the manual subscriber at substa- .Fig. 2, whose telephone number, it.

tion A,

will be assumed, is #23456. When the receiver is removed at substation A, a circuit is completed over the line conductors 11 and 12 for the line relay 14 of the individual line switch C. Upon energizing, the line relay completes at its armature acircuit which extends through theswitching relay 13 and the stepping magnet 15 in series to battery, and at its armature 19 connects the test wiper 26 to the above circuit at a point midway between the switching relay and the said stepping magnet. The operation now depends upon whether the first selector trunk with which the wipers of the line switch are in connection is busy or is not busy. If this trunk line is busy the test contact 31 associated therewith will have a ground potential upon it, the switching relay 13' will be short circuited, and the stepping magnet 15, .which interrupts its own circuit, will operate as abuzzer to advance the switch Wipers -27, inclusive, step by step in search of an idle trunk line. This operationv will continue as long as the test wiper 26 .continues'to engage gropnded or busy test contacts. However, we may assume that in the present case when the call is initiated the selector D is'idle, and the test contact 31 therefore is not grounded.

Under these circumstances, when the line re.

lay-.14 is energized the switching relay 13 is energized immediately afterwards, with the result that the line conductors 11 and 1 2 are disconnected from the winding of the line relay l tand from-ground, resgactively, and are extended by way of armatures 16 and 18 and their working-contacts, wipers 25 and 27, bankcontacts: and 32, and armatures and 62 andtheir resting contacts, to -thefupper and lower windings of the line relay 5 0 of thes'elector D. I

As soon as th line is extended to the selector D as above described, the line relay 50 will be energized and will close the cir cuit of the slow acting release relay 51. Upon energizing, the latter relay prepares the circuits of the selector for operation in its vertical movement-in the usual manner, and also completes'a holding circuit extending back to the line switch C as follows: Ground at G working contact of armature 63 and the said armature, conductor 64, bank contact 31, test'wiper 26, armature l7 and its working contact, winding of the switching'relay l3, and the winding of the stepping magnet 15 to battery. It is understood that the above holding circuit is completed before the slow acting relay 1% has had time to deenergize. In addition tomaintaining the switching relay energized,

the holding circuit also serves to provide ground to the multiples of test contact 31 and also to the multiple test contacts in which the private normal conductor 28 terminates in the banks of the connectors'which have access to the line of substation A, thereby guarding the connection against intrusion in the customary manner.

The calling subscriber may now operate his calling device S in accordance with the first digit of the desired number. Two interruptions are thereby produced in the circuit of the line relay 50, and the said relay is accordingly twice deenergized momentarily, transmitting at each deenergization an impulse of current through the slow acting series relay 52 and the vertical magnet 56 to battery. By the operation of the vertical magnet the selector shaft is raised two steps, whereupon the wipers 7 0-7 2, inclusive, will be standing opposite the level of'bank con-- tacts in which are terminated the trunk lines extending to the manual exchange. The slow acting relay 52 is energized in series with the vertical magnet, retaining-the armature attracted throughout. the vertical movement-of the switch, and upon the closure of the vertical 'ofl'normal springs 59 completes a circuit for the stepping relay 53.

Upon energizing, relay 53 prepares a circuit for the rotary magnet 54 at its lower armature, and at'its upper armature establishes a locking circuit. for itself. At the end of the vertical movement of the switch the slow acting relay '52 is deenergized and closes the circuit of the rotary magnet,

connected is busy or is not busy. If this trunk line is busy the test contact associated therewith will be grounded and the stepping relay 53 will'be energized over a circuit which extends by way of the test wiper 71,"

armature 61 and its resting, contact, interrupter contact of the rotary magnet, foff normal springs59, and the winding of the stepping relay. 5,3 to battery. The stepping relay will therefore again close the circuit of the rotary magnet 54E which will operate to rotate the switch wipers into engagement with the next set of bank contacts. This operation in which the stepping'r'elay and the rotary magnet are alternately energized and deenergized will continue as long as the test wiper 71 continues to engage grounded or busy test contacts. In the present case 'it will be assumed thatthe-trunk line shown inthe drawings is the first idle trunk line, and when therefore the test wiper 71 arrives at test contact 74 andthe rotary magnet isdeenergized, the stepping relay 53 will not again be operated, but instead the switching relay 55, which heretofore has been short-circuited, will be energized by current flowing over the following path:

grounded conductor 64, winding of the. switching relay 55, mterrupter contact of the rotary magnet 54, off normal springs 59, and the winding ofthe stepping relay 53 to battery. Owing tothe high resistance of the switching relay '55, stepping relay 53 is not operated. Upon energizing, relay 55 disconnects the -incoming line conductors from the windings of the line relay 50 and extends them byway of armatures and 62 and their working contacts, wipers and 72, bank contacts 73 and 75, trunk con-- ductors 76 and 78, left hand windings of the repeating coil in the cord circuit 0,

Fig. 2, and normally closed contacts ofithe reversing relay 105 to the upper and loivver windings of the line relay 104: in the cord circuit.

lVhen the calling line is extended to the line relay 104 as above explained, the said line relay is operated, and completes an energizing circuit for the slow acting relay 103. Relay 103, on-attracting its arma ture 115, connects ground to the release trunk conductor 77-, and thus closes a holding circuit for maintaining the switching relays'55 and 13 energized during the call. In addition to the foregoing, relay 103 prepares at its armature 116 an operating circuit for the register switches of whicheverset is later. selected; and at its arma-- ture 117 closes -an operating circuit for the individual line switch C 'which-extends'as followsz ground at G*, armature 117 and its I to that which has already been described in the case of the individual line switch C. Forthe sake of simplicity it 'will be assumed that the wipers of the line switch C are already in connection. with the bank contact set associated with the first register set, as shown in the drawing, and it will be is idle. It will be evident therefore that test contact 226 will not be grounded, and

no rotation of the line switch C will take place. The switching relay 201 is at once ener ized and establishes a locking circuit for itself at itsarmature 206. Relay 201 also performs a number of other circuit changes which may be mentioned briefly as follows: At armature 205 ground is connected tothe test wiper 222 for the purpose of rendering the multiples of test contact 226 busy in the banks of the other rotary line switches. At armatures 204 and 208 conductors 152 and 150 are extended through to wipers 220 and 223, respectively, and at armature 207 the conductor 151 is disconnected from the winding of the line relay 202 and is extended by way of the working contact of armature 207, wiper 221, bank contact 225, and'the winding of relay 235 of the master control switch MS to battery. Upon the closure of its circuit relay 235 is operated and at its armature 240 closes selecting operation will take place similar assumed furthermore that this register set a circuit for the stepping magnet 272 of the timing switch P, the operation of which will be described subsequently. Relay 235 also disconnects ground from the common releasing conductor 280 at armature 242, and at armature 2 11 prepares an operating circuit for the stepping magnet 301 of the register switch B, Fig. 4.

The apparatus is now ready for the receipt of the series of impulses corresponding to the first digit in the local number of the called line in the manual exchange. p understood, of course, that the first digit in the telephone number which operated the selector D at the automatic exchange has to do with the office selection only and does not appear in the multiple at the B operators position. When the dial of the calling device S is operated in accordance with the next digit therefore another series of interruptions, three in this case, will be produced.

in the line circuit and will bring about a like series of deenergizations ofthe line-relay 104 in the cord circuit 0. At each dcenergization the said relay transmits an impulse of current to the stepping magnet 301 of the register switch R over the following path: ground at G armature 118 and its resting contact, armature 116 and its working contact, conductor 152, armature 204 and its working contact, wiper 220, bank contact 224, armature 24:1 and its working contact, winding of the slow acting series relay 236, conductor 285, common strip 260, wiper 256, first bank contact associated with wiper 256, conductor 286, and the winding of the stepping.magnet 301 to battery. By the operation of stepping magnet 301 wipers 304 and 305 of the register switch R are advanced three steps and are brought to rest in engagement with the third contacts in their respective banks. The slow acting relay 236 is energized in series with the stepping magnet 301 and retains'its armature 2 13 attracted while the said magnet is being operated. In operated position relay 236 closes a circuit for the slow acting relay 237, which is thus held in operated position also during the operation of the first regis-- ter switch. After the last impulse has been transmitted,'the slow acting relay 236 will deenergize and will break the circuit of relay 237. Since the latter relay is slow act- .ing, however, a circuit will be closed for an instant which extends from the grounded armature 2 13 by way of the resting contact of'said armature, armature 245 and its working contact, and the winding of the step ping magnet 259 of the master control switch MS to battery. One impulse is thus transmitted to the stepping magnet 259, and wipers 255 and 256 are advanced one step into engagement with the second contacts in their respective'bank's. The advance of wiper 255 is of no effect, but when wiper It is 256 moves from its first contact to the second, the operating circuit is transferred toconductor 287 which extends to the stepping magnet 321 of register switch R The calling subscriber will now operate his calling device in accordance with the next digit in the desired number. As a result, the line relay 104.- in the cord circuit operates the same as before, but now sends four impulses over the operating circuit to 76 the stepping magnet 321iof the register switch R The stepping magnet 321 is thus operated to advance the wipers 324 and 325 four steps and the wipers are brought to rest in engagement with thefourth con- 8 tacts in their respective banks. The slow acting relays 236 and 237 are energized during the transmission of the second series of impulses the same as during the first, and when the impulses cease another impulse of current is transmitted to the stepping magnet 259 of the master control switch, thus advancing the wipers 255- and 256 another step, and transferring the operating circuit by way of conductor 288 to the stepping magnet311 of register switch R It will not be necessary to consider indetail the manner in which register switches R and R are operated. When the digit 5 is called a series of five impulses is transmitted to. the stepping magnet 3 11 of register switch R and wipers 3 1 1 and 3 15 are advanced into engagement with the fifth contacts intheir respective banks. At the end of the series of impulses the master control switch is operated one step and the operating circuit is transferred by way of conductor 289 to the stepping magnet 361 of register switch R. The series of six impulses which results from the calling of the- 195 final digit thus causes the operation of the stepping magnet 361 and the wipers 364 and 365 are advanced into engagement witha-the sixth contacts in their respective banks. The stepping magnet 259 in the master control switch is given another impulse of current also at the end of the last series of impulses and wipers 255 and 256 are advanced one more step.

By the last operation at the master control switch, wiper 255 is brought into engagement with the fifth contact in its bank and ground isplaced on conductor 291, resulting in the energization of relay 238. Upon attracting its armature 2A6 relay 238 stops the operation of the timing switch P, while at armature 2 17 the conductor 28 1 is connected to ground, thus closing a circuit through thelamp L, Fig. 2, and the relay 162 of the consecution control switch COS. By the closure of this circuit relay 162 is energized and lamp L is lighted to notify slow acting, however, and before it has time ductor 171 from ground at armature 248 and extends it instead to the winding of relay 239. Conductor 1.71 may be considered as a test conductor and extends to the first contact in the bank of the consecution con trol switch COS, since the register set shown is assumed to be the firstregister'set at the position. The other test conductors 172-176, inclusive, are of course associated with the other register sets at the same position.

Assuming that no other call is being shown on the indicating device just at the present time the consecution control switch COS is now immediately operated to switch the registered call over onto the indicating device. The operation is as follows: \Vhen relay 162 energizes, it connects up the wiper 164 by means of armature 166, and at armature 165 closes a circuit for the slow acting linerelay 161. Upon energizing, the latter relay closes a circuit' at its armature 168 which includes the switching relay 160 and the stepping magnet 163 in series, and at its armature 167 connects the wiper 164 to the above circuit at a point midway between the said relay and magnet. The latter operation provides for advancing the wiper 164 in case the contact with which it is in engagement is grounded, but it will be assumed in the present case that the wiper is standing on the first contact of the bank as shown in the drawing, and since the round has been removed from this contact 30y the energization of relay 238, no rotation of the switch will take place. Instead, the switch- 'ing relay 160, which is of high resistance,

is at once energized in series with the stepping magnet 163, the latter remaining inoperative, and breaks the circuit of the. line relay at armature 169. The line relay is to fall back relay 239 in the master control, switch is energized over the following circuit: from ground at G by Way of armature 168 and its working contact, work- 111g contact of armature 170 and the said "armature, working contact of armature 166 relay energized after the line relay 161 has deenergized. Relays 238 and 239Vin the master control switch are-now'both energized, andthe consecution control switch is in operated position (switching relay energized) with its wiper in' engagement with thebank contact correspondin to the first register-set. Other calls may e registered on the other register set at anytime now and when registration is completed the lamps L L etc., corresponding to the register sets in use will be lighted, but this.

rating device and the manner in which this is' done will now be pointed out, it being recollected that the wipers 304, 324, 344, and 364, are now resting upon the third, fourth, 'fifth, and sixth contacts in their respective banks. \Vhen armature 252 of relay 239 is attracted, ground'is placed on conductor 281, and as a result parallel energizing circuits are closed for relays 303, 323, 343, and 363 of the register switches R to R, inclusive. By the e'nergization of these four relays ground is connected to the common strips in the upper banks of all of the register switches- It follows, therefore, that with the register switch wipers-in their present operatedposition conductors 313, 334, 355, and 376 will be grounded. These four conductors extend to the indicating device V and terminate in the No. 3 lamp of the first group, the No. 4 lamp of the second group, the No. 5 lamp of the third group, and the No. 6 lamp of the fourth group, respectively. The other side of all the lamps is connected to battery and the lamps mentioned are accordingly illuminated to indicate to the operator the #3456.

The manner in which the operator handles the call thus displayed before her will now be considered. \Vhen relay 239 of the master control switch MS pulls up and closes a circuit for displaying the registered number to the operator, it also closes at its armature 251 a circuit for the trunk or call signal lamp L in the cord circuit 0, which may be traced as follows: from ground by way of the working contact of armature 251 and the said armature, conductor 282,"

bank contact 227, wiper 223, working contact of armature 208 and the said armature, conductor 150, winding of relay 102, resting contact of armature 111 and the said armature, armature 122 and its resting contact,

.andthrough the lamp L to battery. By

knowingby the lighting of the lamp L that the cord circuit is the one in use, the' operator will test the multiple jack of line 3456 with the tip of her plug in the usual manner in order to find out whether or not the line is busy. If the line is found to be in use, the plug will be inserted in a busy back" jack. of? well known form and function, in order to give the calling subscriber a busy signal. Assuming, however, that the line is found to be idle, the operator will at once insert the plug in the jack of the wanted line, which in the present case is the jack J. l

As soon as the plug is inserted in the jack a circuit is completed for the sleeve relay 109 in series with the cut off relay 1400f the called line, and the latter relay is energized to clear the line of its normal battery and ground connections in the usual manner. Relay 109 is energized also and at armature 127 disconnects the operators head set. At the same time at armatures 127 and 129 the tip and ring conduftors of the cord are con-- nected through to the plug, and a ringing circuit is established over which ringing current from the generator- GEN is projected intermittently to signal the called subscriber.

In addition to the functions described, relay 109 also closes a circuit for relay 107 at its armature 128. Upon energizing, relay 107 opens the circuit of the call signal lamp 1] at armature 122, and at armature 12$ 1 closes a circuit for relay 101', which includes the grounded conductor 150. Upon energizing, relay 101 establishes ,a locking circuit for itself at its armature 113, and at the back contact of the same armature disconnects ground from the holding conductor The last operation, above mentioned, brings about the release of the switches in the register set, upon which the called num-' her was registered, and the release of these switches will now be explained. When' ground is disconnected from conductor 151,

the holding circuit for relays 201 and 235 of the line switch C and the master; control switch MS, respectively, arebroken and these relays are deenergized. Relay 201, upon deenergizing, disconnects the wipers ot' the line switch C, which isthus restored to normal condition. \Vhen relay 235 deenergizes it connects ground to the common conductor 280 at its armature 242. A circuit is thus established throughthe release magnet 271 of the timing switch P, through the release'magnet 258 of the master-control switch MS, and through the release magnets 302, 322, 342 and 362 of the register switches R1 to R, inclusive, respectively, and the said magnets are accordingly operated to restore their associated switches to normal position. The circuit of each release magnet, except the release'magnet of the timing switch P, is taken through a pair of rotary off normal springs and as each switch returns to normal position it separates its oft normal springs in order to open the circuit of the associated release magnet. Anequivalent arrangement is provided in the case of the case there isno other call waiting at this time relay 162 of the consecution control switch CCS will be dcenergized. If a call is waiting, however, relay 162 will be held up in series with one of the other lamps shown, such as lamp L or lamp L for example, and when relay 160 falls back, the line relay 161 will again be energized. Since the first test contact in the bank t-raversed by wiper 164 has just been grounded bythe deenergization of relay238, the operation of the line relay 161 causes the consecution control switch CCSto advance its wiper into engagement with the test contact which is, associated with the first register set upon which .a registered call is waiting and this call is thenQs'WitChed on to the lamps of the indicating device, the same 3 as has been describedl Returning now to the cord circuit (1. has been explained how the connection has: been completed to the line of the called substation A, and ringing current is projected out over the called line 'to signal the subscriber. During the ringing operation a tone is induced in the lett-hand windings of the repeating coil of the cord circuit 0, by reason of the fact that the ringing circuit includes the upper right-hand winding of the repeating coil, and this tone is audible to the calling subscriber, who is thus advised that the signalling operation is proceeding satisfactorily. The ring cut-off relay 108 is included in the ringing circuit and when the called subscriber answers this relay pulls first instance through its lower winding alone, since the upper winding is. normally poses, and is provided in accordance with standard practice, although it is of no utility in the particular system shown herein.

The required connection having been established, the subscribers may now converse as desired. \Vhen the conversation is finished both subscribers will-hang up theirreceivers, and the replacement of the receiver at the calling station A causes the automatic switches to be restored to normal. \Vhen the receiver is replaced the circuitof the line relay 104 is broken, resulting in the deenergization of this relay and also in the deenergization of the slow acting relay 103. Relay 103, on deenergizing, closes a circuit for the supervisory lamp L at armature 117, and at armature 115 disconnects ground from the release trunk conductor T'T.- By the latter operation the holding circuits of relays 55 and 13 in the selector .1) and line switch C, respectively, are broken and the said relays are permitted to decnergize, whereupon the switches named are restored to normal in the usual and well understood manner. An instant later slow acting relay 100, whose circuit was broken at the working contact of armature 117 of relay 103 falls back and again connects ground to the release trunk conductor 77 at arma ture 110. This operation renders the trunk line busy so that no more calls can come in while the plug is in the jack.

The automatic switches have now been released, a disconnect signal has been given to the operator, and the trunk line in use has been made busy pending the pulling down of the connection. \V hen the operator ohserves the lighted supervisory lamp L she will remove the plug of the cord circuit 0 from the jack and relays 109, 108. and 107 are deenergized and restored to normal. By the falling back of relay 1.07 the circuit. of the supervisory lamp L is broken at armature 123, and at armature 121 ground is disconnected from the release trunk eonductor 77, the latter operation being eilec tive to restore the trunk line to idle condition. All the apparatus has now been restored and is ready for use in handling an-' other call,

In case the operator should accidentally This operation may be used for. operating a meter, or for other similar pur-.

will be flashed to attract the attention of the operator. If the operator remembers the jack from. which the plug was withdrawn she can re-plug immediately, otherwise. she will plug into a special jack (not ',shown) which connects with her head set so that she can talk to the calling party and askhim what number "he was disconnected from..

Certain details of the system will now be explained which it was not convenient to go into before, and the first thing which will be considered is the function of the timing switch P, Fig. 3. This switch is provided for the purpose of handling the so-called mutilated calls, which are calls arriving at a register set and which, because of improper dialling by the calling subscriber, or failure of some switch to function properly, are not completely registered. It will be understood that in the ordinary operation of the system a call is dismayed to the operator by the energizalion of relay 238 followed by the energization of relay239 at the proper time under control of the consccutiou control switch pulses being transmitted through the master control switch MS, which cause the. wiper to engage the fifth contact in its bank to ground conductor 291; and it will be appreciated, therefore, that if less than four digits are registered, relay 238 will not ordinarily be energized. and the partiaL ly registered number will never be displayed to the operator. Experience has shown, that these" incomplete calls are av fruitful source of trouble, since each such call occupies a register set until the calling subscriber hangs up his receiver, without giving the operator a signal of any kind. In order to eliminate the ditliculty pointed out, the timing switch 1 is provided and this switch is adapted to bring switch begins to operate under the control to the operator in due course.

a at ia of the time control impulse sender, indicated by the reference character T. This impulse sending mechanism is so arranged that the conductor 270 is grounded at one second intervals with the result that after the expiration of ten seconds the wiper 274 closes a circuit'by which ground is connected with conductor 291. This causes relay 238 to be energized, and whatever digits have been registered in the meantime are displayed It Will be obvious that the time interval can be varied as desired, but the interval of ten seconds herein mentioned is believed to be about right, since it has been determined by 0b serving a large numberof calls that this time interval is long enough to allow Ordinary calls to be completely registered in practically all cases. Of course, if the subscriber is very, slow "in calling a number the time interval will have elapsed before he is through, butthis causes no particular harm, since the circuit arrangement is such .that the subsequent registration of the digits is not interfered with. It is intended that .the mutilated callswill be extended by the operator to a: complaint or trouble operatorby plugging into trunk lines provided for this purpose, in order that the regular operator may be free to confine her I I attention to handling'the regular tratfic.

Another feature of the invention relates to a'no vel circuit arrangement in the cord circuit 0, which provides for lighting the 'supefivisory lamp L in place'of the trunk "or call signal lamp L in case the latter is burnt out, or its circuit is open at some point. It will be-observed that the circuit for' lighting lamp L at the .proper time is completed over conductor 15O and includes the winding ofrelay 102, while at armature 114; of this relay a branch circuit extends by We of conductor 139 to lamp L Now, if t mm is nothing wrong with' the circuit of lamp L relay 102 is energized in series with thesaid lamp, and the i. branch path through lamp L. is broken,

but if the circuit of lamp L is'open atany point beyond relay 102, the said relay will not pull up, the circuit through lamp L will not be opened, and the latter lamp will be lighted. The lighting of this supervisory lamp simultaneously with the display of a number on the indicating device will give the operator the required information as to which trunk line is in use by the calling party whose wanted number is displayed, and she will proceed to complete the connection in the usual manner. It will be understood that were it not for this pro vision, if the lamp L should be burnt out the operator would be atv a loss to know .which of the trunk lines was in use by the calling subscriber, and she would be unable to complete the connection corresponding to the number: displayed The feature described provides means for taking care of the connections temporarily until defective call signal lamps can be replaced, or their circuits repaired.

Another feature which is also included in' trouble has been experienced due to the accidental grounding of the sleeve of the cord circuit in use, resulting. in the release ofi a partially operated register set. F or in? stance, an operator could release all the registered or partially registered calls at her position by merely taking the tip ofj one of her cord circuits and running it over the sleeves of all of the jacks in front of her in quick succession, and this, possibility has been availed of by unscrupulous operators in order to clear their positions of accumulated calls. This is, of course, very detrimental to-the service, and is efi'ectually prevented by the circuit arrangement shown herein for energizing the relay 101. An expmination of the circuit'will show that rey the trunk lamp L is lighted, since its circuit is completed over the grounded conductor 150 at armature 124.. Thus, it will be seen that the accidental or deliberate grounding of the sleeve conductors of cord 101 can only be energized at the time circuits upon'which registered or partially registered callsare waiting willbe of no Having described my invention, what I consider to be new and desire to have protected by Letters Patent will be pointed out in -the appended claims.

What I claim as myinvention is:

1.111 a telephone system, a register set accessible to a calling automatic subscriber for registering-the digits in a called telephone number, an indicating device for disa playing the registered number to an opera tor, means for, causing all such digits as have been registered to .be displayed after a definite time interval has elapsed, and means for displaying the complete number at once in case all the digits thereof are registered before the expiration of the time interval.

2. Ina telephone system, aplurality of register sets at, an exchange accessible to calling subscribers for registering called telephone numbers, a common indicating device for displaying'registered numbers to an operator, means automatically responsive to the registration of final digits for causing completely registered numbers to be displayed, and time controlled means for causing the registered digits of all partially registered numbers to be displayed.

3. Ina telephone system, a plurality of register sets at .an exchange accessible to calling subscribers for registering called telephone. numbers, a common indicating device for displaying registered numbers to an operator, means whereby a calling subscriber may cause a registered number to be displayed by registering the final digit thereof, and time mechanism for causing the registered digits of any partially registered number to be displayed after a definite time interval.

4;. In a telephone system, a register set accessible to a calling automatic subscriber forregistering the digits in a called telephone number, an indicating device for displaying the register number to an operator,

means for causing the complete number to be displayed when the last digit thereof is .registered,;and means for displaying the incomplete number after a definite time interval in case the subscriber fails to register one or more of the digits.

5. In a-telephone system, a register set accessible to a calling automatic subscriber for registering the digits in a called telephone ,number, said set comprising a switch for each digit, an indicating device for displaying the registered number to an operator, means for causing the complete number to be displayed when the last digit thereof is registered, a time mechanism-set in motion when the first digit switch is seized, and means controlled by said mechanism 1 for causing all registered digits to be displayed in case the subscriber fails to register them all.

6. In a telephone system, an operators position, means'including a trunk line terminating at said position for extending a connection to a calledline, call and super visory lamps for said trunk line, means for lighting the call lamp before the connection is established, means for lighting the supervisory lamp when the subscribers are through talking, and means for lighting .lamp in case the latter the supervisory lamp in place of the call fails to light at the proper time.

7. In a telephone system, an operators position, means including a trunk line terminating at said position and associated equipment for connecting a calling and called line, a call signal associated with said trunk line and means for operating it to call the operator, a disconnect signal and means for operating it when the conversation 18 finished, and circuit connections for ing the supervisory lamp in place of the call I lamp, in case the latter is burnt out.

9. In a telephone system, an operators position, means including a trunk line terminating atsaid position for connecting a calling and a called line, a call lamp for said trunk line and means for-lighting it to call the operator, a supervisory lamp and means for lighting it when the conversation is finished, and circuit connections for lighting the supervisory lamp in place of the call lamp in case the circuit of the latter is open,

10. In a telephone system, an operators position, a trunk line accessible to automatic subscribers lines and terminating in a plug ending cord circuit at said position, a register set associated with said, cord circuit and controllable by a calling subscriber to register a called telephone, number, a holding circuit for preventing the restoration of said register set, means for opening the said holding circuit to restore the register set .when the operator plugs into the called line, and means for preventing the opening of said holding circuit by accidentally closing a circuit through the plug before the called number is completely registered.

11. In a telephone system, an operators position, trunk lines terminating in plug ending cord circuits atsaid position, a reg ister setcommon to said cord circuits, means whereby a calling subscriber connected to one of said trunk lines can obtain access to said register set and control the same to register a called number, means for preventing other subscribers from using said register s'et meanwhile, means for rendering said register set available to other subscribers when the operator plugs into the called line, and means for preventing the operator from interfering with the exclusive use of said register set the calling subscriber before the registration of the called number is completed.

12. In a telephone system, an operators position, trunk lines terminating in plug ending cord circuits at said position, a register set common to said cord circuits, means whereby a calling subscriber connected to one of said trunk lines can obtain access to said register set and control the same to register 'a called number, means for preventing other subscribers from using said register set meanwhile, means for displaying the registered number to the operator, means for rendering said register set available to other subscribers when the operator plugs necting a calling and'called line comprising a plug ending cord circuit, a repeating coil in said cord circuit, a double wound relay connectedbetween two windings of said repeating coil in series with the batteryto feed current to the called line, one windin of said relay being normally short circuite a ringing circuit including one winding of said repeating coil and the short circuiting path around said relaywinding, the calling subscriber being given an audible signal by induction between the\ repeating coil windings, means fior includin the other winding of said relay in the ClICUltotthe called line when the called subscriber answers, and contacts for opening said short circuit when the relay is energized.

14. In a telephone system, a trunk line, a plug ending cord circuit for connecting trunk' line with a called telephone line, a sleeve .relay for closing said ringing circuit, a battery feed relay, a ring cut oil relay and a normally short circuited winding of said battery feed relay included in said ringing circuit, a repeating coil and a winding thereof also includedin said ringmg circuit whereby a ringing signal is transmitted to a calling subscriber.

connected to the trunk line, a normally short circuited locking Winding for the ring cut ofi' relay which isiincluded in series with the sleeve relay when the ringing cut off relay is energized by the response of the called subscriber, contacts controlled by the operation of the ring cut oil relay for opena second windingof saidbattery feed relay to supply current to the called line through lay for opening the other branch.

16. In a telephone system, an operators switchboard, a trunk circuit terminating at said board, a call signal and a disconnect signal individual to said trunk circuit, means call is received over said circuit, and means for actuating said disconnect signal in place mg the ringing circuit and for connecting for actuating the call signal when a,

of the call signal in case the latter fails to operate.

. a call is received, and means for actuating said second signal in place of the first in case the latter fails to respond-to a call.

18. In a telephone system, a' register set accessible to a callin automatic subscriber for registering the igits in a called telephone number, a normally inoperative indicating device for displaying a registered number to an operator, means automatically responsive to the registration of the final digit in a number for rendering the device operative to simultaneously display all the registered digits, and time controlled means for rendering said device effective to cause the registered digits ofany partially registered'number to be displayed after a predetermined time interval.

'19. In a telephone system, a register set accessible to a calling automatic subscriber for .registering the digits in a called telephone number, a normally inoperative indicating device for displaying a registered number to an operator, means automatically responsive to the registration of the final digit in a number for rendering thedevice operative to simultaneously display said mechanism for, rendering said device operative to cause the'registered digits of 'an incomplete number to be displayed after a predetermined time interval.

20. In a telephone system, a register set accessible to a calling automatic subscriber for registering the digits in a called telephone number, a normally inoperative indicating device for displaying a registered number to an operator, means automatically responsive to the registration of the final digit in a number for rendering the device operative to simultaneously display all the registered digits, and means automatically effective responsive to the lapse of a predetermined time interval for rendering said device operative in case the subscriber fails to register one or more of the digits.

21. In a telephone system, an operators switchboard, a trunk line terminating at said board, a call signal associated with said trunk line, a register set adapted to be for use to register the digits in a'wanted telephone number, means for operating said .signal automatically after a number is fully registered, and time controlled means for operating said signal after a predetermined time in case the calling party fails to register one'or more digits in the said number.

22. In a telephone system, an operators switchboard, a trunk line terminating at said board, a call signal associated with said trunlr' line, a register set adapted to=be associated with said trunk line and controlled thereover when the same is taken for use to register the digits in a wanted telephone number, means for operating said signal automatically after a. number is fully registered, and time controlled means for operating said signal after a predetermined time in case said trunk line is seized and the calling party fails to register any digits.

23. In a telephone system, an 'operators switchboard, a trunk line terminating at said board, a register set adapted to be associated with said trunk line and controlled thereover-when the same is taken for use to .the final digit in the number is registered.

means for preventing. the relea t ally reglstered number register the digits in a wanted telephone number, operator controlled means in the trunk circuit forcausing the release of said register set, and circuit arrangements whereby said means is renderedineflective until become momentarily grounded.

,25. In a telephone system, means including'a cord circuit for connecting a calling and called line,-' a repeating coil, a double wound battery feed relay, said relay having one winding normally short circuited and having both windings connected in series with two windings of said repeating coil, a

- ringing circuit including one winding of said repeating coil, the calling subscriber receiving a signal by induction between the repeating coil windings, and contacts on said relay operated when the relay energizTesiipon theresponse of the called subscriberto' remove said short circuit to bal ance the talking circuit.

26. In a telephone system, an operators trunk circuit, means including an automatic switch controlled by a calling subscriber for extending a call to said trunk circuit, a lamp signal in said trunk circuit, means for lighting said lamp to give a steady signal to indicate to the operator that a connection is desired, a plug and jack for connecting said trunk circuit with a called line, andmeans for flashing said lamp in case the operator should remove the said plug from said jack before the calling subscriber releases said tion before the calling subscriber hangs up.-

28. In a plug ending trunk, a call signal, a circuit for said signal; having two branches, one of which is normally con nected, means controlled over the trunk for placing a potential on said normally connected branch to operate said signal, a relay energized responsive to the insertion of ,the plug in a jack, contacts on said relay for opening said circuit, a second relay energized by said first relay, a locking circuit for said second relay controlled ver the trunk, contacts on said second relay for disconnecting said normally connected branch and for connecting the other branch, and an automatically interrupted source of potential in the second branch.

29. In a register set for registering the digits in called telephone'numbers, a series of register switches, a master control switch, means including a hunting switch for associating a calling line with said switches, an operating circuit extending through said hunting switch and said master-switch to the first of said register switches, means in said master switch for transferring said operating circuit to each of the other register switches, a magnet for operating said means, and two relays jointly controlling said magnet. 1

' 30.In a register setfor registering the digits in called telephone numbers, a series of register switches, a master control switch, a single operating circuit normally extending throughsaid master switch to the first of said register switches, means for transmit ting series of impulses over said circuit corresponding to digits ,in a called number to operate said switches, means in said master switch for transierring the operating circuit.

to the other register switches in regular order,'and means for operating said last means automatically after each register switch is operated. 1

. 31. In a register set for re istering the digits in called telephone numbers, a series of register switches, amaster control switch", an operating circuit normally extending through said master switch to the first of said register switches, means in said master switch for transferring the operating on- 1,54ae4e cuit to the other register switches in regular order, means for operating said last means automatically after each register switch is operated; release circuits for saidiregister switches, and means associated with said master switch for closing all of said release circuits simultaneously.

32. In a register set for registering the digits incalled telephonenumbers, a plurality of register switches, a master control switch, an operating circuit extending to said master switch, a circuit changer in said master switch for further extending the said circuit to said register switches in succession, a relay in said operating circuit, and a second relay controlled by said first relay and cooperating with said first relay to control said circuit changer.

33. In a register set for registering the digits in called telephone numbers, a plurality of register switches, a master control switch, an operating circuit extending to said master switch, a'circuit changer in said master switch for further extending the said circuit to said register switches in succession, and a pair of slow acting relays for controlling said circuit changer each time a digit is registered.

34. In a register set for automatic tele-.

phone systems, a series of register switches responsive to successively called digits in a telephone number, operating magnets in said switches, a master switch, an operating circuit normally extending through said master switch to the operating magnet of the first switch, and means controlled over said operating circuit for operating said master switch for extending said circuit to the operating magnets of the other switches successively.

35.-In a register set for automatic telephone systems, a series of register switches responsive to successively called digits in a telephone number, operating magnets in said switches, a master switch, an operating circuit normally extending through said master switch to the operating magnet of the first switch, and means for operating said master switch for extending said circuit to the operating magnets of the other switches successively, said means comprising a relay in series with said operating circuit.

36. In a register set for automatic telephonesystems, a series of re ister switches responsive to successively cal ed digits in a telephone number, operating magnets in said swltches, an operating circuit normally extending to the operating magnetbfthe first switch, a master switch ior extending said circuit to the operatmg magnets of the other switches successively, means for operating said master switch whenever one of said register switches is operated, release magnets in said register switches, and means associated with said master switch for energizing all said release magnets simultaneously.

37. In a telephone system, a register set controlled means for rendering the other set of switching devices eliective to operate its associated indicating device.

38. In a telephone system, a register set for registering called telephone numbers and comprising a plurality of switches, a pair of indicating devices on which registered numbers are displayed to an operator, duplicate sets of wipers in said switches for controlling said devices, respectively, only one set of wipers being normally efi'ective, and an operator controlled circuit changer for rendering the other set of wipers effective to operate its associated device.

39. In a telephone system, a registerset for registering called telephone numbers and comprising a plurality of switches, a pair of indicating devices on which registered numbers are displayed to an operator, each device comprising a plurality of sets of lamps, wipers in said switches for controlling the circuits of the lamps in one of said devices, additional. wipers in said switches forcontrolling the circuits of the lamps in the other device, normally open and closed contacts in the circuit connections to the two groups of wipers associated with the two devices, respectively, and a switch for closing the normally open connection and opening the normally closed connection.

In witness whereof, I hereunto subscribemyname this 25th day of April, A. D. 1921.

BERNARD D. WILLIS- 

